The present invention relates to an electric pump and a cleaning device for an on-board optical sensor.
On-board optical sensors are now often arranged on the front or rear of vehicles to use the images captured by the on-board optical sensors. Foreign material such as mud may collect on an external image capturing surface (lens or protective glass) of such an on-board optical sensor. Thus, an on-board optical sensor cleaning device has been proposed to eject air toward an external image capturing surface from an ejection port of a nozzle (refer to, for example, Japanese Laid-Open Patent Publication No. 2012-35654).
An air pump (electric pump) connected to a nozzle that ejects air has also been proposed (refer to, for example, Japanese Laid-Open Patent Publication No. 2001-41159). The air pump includes a tubular cylinder, a piston that is movable back and forth in the cylinder, an electric drive device that drives and moves the piston back and forth, a discharge port through which the inner and outer sides of the cylinder are in communication, and a discharge valve that functions to open and close the discharge port. The discharge valve of the air pump is a ball that is biased to perform a closing action. When the air in the cylinder is compressed, the pressure of the compressed air results in the ball performing an opening action. More specifically, in the air pump, when the driving force of the electric drive device moves the piston to narrow the void in the cylinder, the air in the cylinder is compressed. The pressure of the compressed air opens the discharge valve and discharges compressed air from the discharge port.
However, in an air pump such as that described above, the pressure of the compressed air opens the discharge valve. Thus, air may leak from the discharge valve when undergoing compression. This may hinder the momentary discharge (ejection) of high-pressure air having the set (expected) amount and pressure. Further, the on-board optical sensor cleaning device may therefore fail to clean the external image capturing surface.